JP2003526178A - Contact mechanism for electronic overload relay - Google Patents

Abstract

Abstract: An overload having a housing (10) and a bistable armature (18) mounted on an axial pin (16) of the housing (10) so as to be pivotable between two stable positions. The relay trip mechanism realizes a low-cost configuration and high reliability that are easy to assemble. The fixed contacts (12, 14) are located in the housing (10) and the movable contact (48) is in one of two stable positions to a closed position in contact with the fixed contact (12, 14) and two stable positions. The other of the positions is supported by a leaf spring (32) so as to be movable to an open position with respect to the fixed contacts (12, 14). The protrusions (50, 52) supported by the armature (18) operate to move the leaf springs (32) and their associated contacts (48). The latch arm (24) supported by the armature (18) has a latch surface (84, 86). The spring (94) is attached to the housing (10) and has a latch finger (88) that engages the latch surface to hold the armature in one of two positions.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION

The present invention relates to electrical relays, and more particularly to an overload relay trip mechanism.

[0002]

BACKGROUND OF THE INVENTION

Overload relays are electrical switches commonly used in industrial equipment to protect the electrical equipment from being damaged by heating conditions caused by excessive current. Typically, the electrical equipment is a three-phase motor, which is connected to the power source via another relay, commonly called a contactor. A typical contactor is a high power relay that has three power flow paths that open and close each circuit connected to a three-phase power source. The movement required to open and close the contacts is magnetically imparted by passing a current through a coil, which is normally energized by a current controlled by another switch at a remote location.

In the conventional manner, the overload relay is connected in series with the control switch of the contactor coil. When an overload relay detects an overload condition, it stops the power supply to the contactor coil, opens the contactor, disconnects the electrical equipment controlled by this contactor from the power source, and damages the electrical equipment. Prevent.

Conventionally, overload relays have used for each phase a resistive heater in heat transfer relationship with the bimetal element that controls the switch. For example, when sufficient heat is transferred from the resistive heater to the bimetal element and an overload condition is sensed, the bimetal element opens the associated switch to deenergize the contactor coil and disconnect the associated electrical device from the power source. .

As a more recent trend, resistive heater bimetal element relays have been replaced by electronic overload relays. For example, US Pat. No. 5,179,495 dated Jan. 12, 1993, which is incorporated herein by reference in its entirety.
Zuzuly). Since the output of such circuits is usually relatively low power, a solid state switch is required for the output to control the current in the contactor coil. The solid state switch controls the current to a relatively low power contact mechanism which not only controls the current to the contactor but also activates the indicator.
Usually, this indicator is a light emitting type indicator and emits light when power is cut off due to overload. An example of such a contact mechanism is assigned to the applicant of the present application and is
US Patent Application No. 08 / 838,90 currently pending, filed April 11, 1997
No. 4 (Lawyer Case No. 355.00069), the entire application of which is incorporated herein by reference.

The mechanism described in this application fulfills its intended purpose very well. However, the use of so-called "bridge" contacts makes assembly a bit tricky,
High cost. Moreover, bridging contacts present reliability problems when closing (rather than opening) the circuit at low currents or loads, especially in connection with solid state devices. More specifically, the bridging contact uses two spaced fixed contacts with one moving contact bar. The contact bar must make good electrical contact with both fixed contacts in order to complete the circuit, and if either contact is degraded due to an arc or the like, or the switching mechanism is dirty. If there is, the circuit cannot be closed. Since there are two contacts, there is twice the possibility of failure as compared to the case where only one contact is used.

The present invention is directed to overcoming one or more of the problems set forth above.

[0008]

[Outline of the Invention]

It is a primary object of the present invention to provide a new and improved trip mechanism for overload relays. More specifically, it is an object of the present invention to be easy to assemble and low cost,
An object is to provide an improved trip mechanism for an overload relay having high reliability.

An embodiment of the present invention is for an overload relay having a housing, a bistable armature pivotally mounted between two stable positions on a shaft pin of the housing, and fixed contacts in the housing. The above tripping mechanism achieves the above object. The movable contact supported by the leaf spring is provided so as to be movable to one of two stable positions, which is in a closed position where it contacts the fixed contact, and the other of the two stable positions, which is in an open position relative to the fixed contact. Has been. The leaf spring is in a position where it can be engaged by the armature. The latching surface is carried by one of the armature and housing and a spring is attached to the other of the armature and housing. The spring has latch fingers that engage the latch surface to hold the armature in one of two positions.

In the preferred embodiment, the leaf springs are spaced from each other on either side of the axle pin. The armature has at least two protrusions, each protrusion engaging a corresponding leaf spring on each side of the axle pin.

In a preferred embodiment, the fixed end of the leaf spring is fixed to the housing and the movable end supports the movable contact. The movable end has a bifurcated shape to define two contact fingers, with one movable contact on each finger.

According to another aspect of the invention, a pull for an overload relay having a housing and a bistable armature mounted on a shaft pin of the housing so as to be pivotable between two stable positions. A removal mechanism is provided. Fixed contacts are provided in the housing, one end of each of the pair of leaf springs is fixed to the housing, and the other end is a free end. At the free end of the leaf spring, the movable contact moves to a closed position where it contacts the fixed contact in one of two stable positions and to an open position relative to the fixed contact in the other of the two stable positions. Supported as much as possible. An actuator is mounted on the armature so as to move with the armature to engage a corresponding leaf spring,
A latch arm having a latch surface is supported on the armature. A torsion spring is attached to the housing and a latch finger on the spring engages the latch surface to hold the armature in one of two positions. A push button is reciprocally mounted on the housing to engage and disengage the latch finger. The push button pushes down to engage the latch finger, disengaging the latch finger from the latch surface and releasing the latch arm.

Further objects and advantages of the invention will be apparent from the following description, some of which are apparent from the description or will be apparent from practice of the invention. The objects and advantages of the invention may be realized from the elements and combinations particularly pointed out in the appended claims.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, an overload relay, shown in a tripped position, and more specifically in an automatic tripped position, has a housing, generally at 10, that is fragmented. The housing has
A first set of normally open fixed contacts, generally indicated at 12, and a set of normally closed fixed contacts, generally indicated at 14, are attached. The housing has an axial, bistable armature pivot pin 16 generally indicated at 18. Armature 18 operates to maintain a first set of movable contacts, generally indicated at 20, in an open position. In the other bistable position, armature 18 operates to open a second set of normally closed moving contacts, generally indicated at 22. These movable contacts 20 and 22 are in contact with the fixed contacts 12 and 14, respectively, to close the circuit, and are opened apart.

A latch lever, indicated generally at 24, is movably coupled to the armature and swings about the axle pin 16 between two stable positions of the armature 18.

The housing is provided with an opening 25 for reciprocally receiving a manual operating means generally indicated at 26, which operating means comprises a push button 28 and a shank portion 30 depending from the button. . The push button 28 is mounted so that it can be moved toward or away from the latch lever 24. With reference to the movable contacts 20, 22, their structure is generally substantially identical, each one having one end 34 attached to a portion 36 of the housing and the other end free end 3.
8 has an elongated leaf spring 32. In one embodiment of the invention as shown in FIG. 2, the free end has a bifurcated shape such as 42 and has two contact fingers 44,
Define 46. Each contact finger carries a contact 48 which closes to a corresponding contact or a corresponding set of fixed contacts 12, 14 as the case may be. Normally,
The normally open contacts 12, 20 operate to power an indicator, such as an electroluminescent means, to illuminate when the relay is in the tripped state. On the other hand, normally closed contacts 14, 2
2 is used to power electrical equipment, typically a controlled motor, by supplying power to the contactor coil to energize the contactor. Leaf spring 32 does not necessarily have a free end 38 which is bifurcated and only one of the contacts 48 may be attached, but only one of the contacts 48 on a given leaf spring 34 cooperates. This bifurcated structure is preferable because the circuit is completed when the fixed contacts 12 and 14 are contacted. As a result, even if one contact is contaminated with corrosion or environmental stains, the other contact can still close the circuit, providing high reliability.

The use of the leaf spring contact structure reduces the number of parts required for each set of contacts 12, 20; 14, 20 and facilitates assembly and lower cost than using bridging contacts. You will see that

The armature 18 supports a total of two protrusions 50, 52, one on each side of the axle pin 16. The protrusion 50 is adapted to engage and open the leaf springs 32 associated with the contacts 12, 20, while the protrusion 52 engages the leaf spring 32 engageable with the contacts 14, 22. And are operable to open these together.

The armature 18 is composed of a first magnetic pole piece 62 and a second magnetic pole piece 64 which is in parallel with and separated from the first magnetic pole piece 62. The pole pieces 62, 64 sandwich not only the shaft pin 16 but also two permanent magnets 66. The two permanent magnets 66 may be of unitary construction, but for convenience and use of two magnets to house the axle pin 16.

Attached to the housing is a shallow U-shaped magnetic yoke or pole piece 70 having legs 72, 74. The coil 76 is provided around the curved portion of the pole piece 70. The winding 76 may be formed of a single coil, or it may be two electrically separate coils wound one on top of the other. The specific configuration depends on the control mode of the electronic circuit used. If one reverses the current through coil 76 to switch the relay from one state to another, only one coil is needed. On the other hand, when switching from one coil to the other without reversing the current, two coils wound in opposite directions are used as the coil 76.

Regarding the latch lever 24, as described above,
It is movable with the armature 18 between two stable positions. One position is shown in FIG. 1, but in the other position the protrusion 52 opens the contacts 14, 22 and closes the contacts 12, 20.

The latch lever 24 has an elongated notch 82 at its upper end, which is located below an opening (not shown) in the housing 10. By inserting a tool, such as the tip of a screwdriver, into the notch 82 through this opening and applying a force to the lever 24, the lever can be shifted between two stable positions for manual testing.

Immediately below the notch 82 is a latching surface defined by two adjacent surfaces 84, 86. Below the latch surfaces 84, 86 are spring latch fingers 88.
The upper end 90 of the finger is adapted to capture and latch the surface 86 of the latch surfaces 84,86 under certain conditions described below. The latch finger 88 extends from a coil 92 of a torsion spring 94, shown generally at 94, mounted on a post 96 in a pocket of the housing 10. Alternatively, the spring 94 may be attached to the latch lever 24 and the latch surfaces 84, 86 may be attached to the housing 10.
It may be formed on top.

The end 98 of the coil 92 opposite the latch finger 88 abuts the housing 10 to prevent rotation of the coil 92 on the post 96. The latch finger latches the latch lever in one of two stable positions on the armature 18, which is not the position shown in FIG.

The latch lever 24 supports a flat, diagonally extending projection 100 immediately adjacent to a post 102 substantially parallel to the axle pin 16. The second torsion spring, shown generally at 104, attached to the post 102 has one end 106 fixed to the protrusion 100 so that the coil 108 of the torsion spring 104 cannot rotate about the post 102. . The opposite end 110 of the torsion spring 104 acts as a reset finger, but extends diagonally beyond the end of the protrusion 100 towards the push button actuator 26 in a diagonal direction. In this regard, the shank portion 30 of the push button actuator 26 cooperates with the reset finger 110 as a stop surface to cause the latch lever 24 to be shown in FIG. 1 from a tripped position rather than the position shown in FIG. Shift to reset position.

For push button actuator 26, and particularly shank portion 30, this lower end has a ledge 114 against which bias spring 116 abuts. This bias spring 116 applies an upward biasing force to the push button to bias the push button 26 upward from the position shown in FIG.

The operating means 26 has an outwardly extending tongue or ledge 120 just above the shank portion 30. At the same time, the housing 10 has a first notch with a retaining surface 122 and a detent surface 124 with a second notch. Since the protrusion 120 of the push button actuator 26 abuts the notch 122 at its uppermost position,
A push button is retained within the housing 10.

The operating means 26, except for the ledge 120, preferably has a substantially cylindrical cross section, which allows not only reciprocating movement but also rotational movement within the housing 10. As a result, when it is pushed down to the position shown in FIG.
Are moved below the detent surface 124. In this position, the operating means is constrained to its lowest position corresponding to the automatic reset mode shown in FIG.

In the automatic reset mode, the ledge 120 causes the upper end 90 of the latch finger 88 to move.
Pay particular attention to the contact with. As can be seen in FIG. 1, this keeps the latch fingers 88 off of the latch surfaces 84, 86 on the latch arm 24. However, when the push button 28 rotates to disengage the ledge 120 from the detent surface 24 and upwardly within the housing 10 due to the biasing force of the spring 116, the upper end 90 of the latch finger 88 contacts the surface 84. Fit in position. Once the relay is tripped, the armature 18 is moved to the other bistable position (not the position shown in FIG. 1) so that the spring fingers 88 cam along the surface 84 and ultimately the latch surface. Moving behind 86, latch lever 24 is held in the tripped position.

To reset the relay, push the push button down, assuming it is in the uppermost position. When the ledge 120 abuts the upper end 90 of the spring finger 88, the spring finger 88 disengages from the latch surface 86. At the same time, since the end 110 of the spring 104 is captured by the notch 112, further pressing down of the push button 26 moves the end of the spring 104 towards the horizontal position, causing the latch lever 24 to move to the position shown in FIG. To drive at the same time.

Other structural and operational features of this mechanism may be verified by reference to Applicants' previously mentioned pending application.

From the above, it can be seen that the overload relay of the present invention uses the leaf spring 31 that supports the contact 48, and therefore is extremely easy to assemble and is low in cost. In addition, compared to the bridge contact type mechanism, the number of parts used is small, so the reliability is high. This reliability is due to the fact that the leaf springs support two contact fingers 44, 4 each supporting one contact 48.
It is further augmented by having a bifurcated free end 38 which defines 6.

[Brief description of drawings]

FIG. 1 is a somewhat schematic cross-sectional view of the tripping mechanism of the present invention, showing the configuration of the components in the automatic reset position.

FIG. 2 is a fragmentary plan view showing a preferred configuration of a set of contacts for use in the device of the present invention.

Claims (10)

[Claims] 1. A trip mechanism for an overload relay, comprising: a housing; a bistable armature attached to an axle pin within the housing for pivotal movement between two stable positions; An armature so that it can be moved into the fixed contact and in one of two stable positions into a closed position in contact with the fixed contact, and in the other of the two stable positions into an open position relative to the fixed contact. A movable contact supported by a leaf spring arranged to be engaged with the latch arm, a latch arm supported by one of the armature and the housing and having a latch surface, and a latch arm attached to the other of the armature and the housing. An overload relay trip mechanism comprising a spring having a latch finger that engages a surface to hold the armature in one of two positions. 2. The leaf springs are spaced apart from each other on both sides of the axle pin, and the armature has at least two protrusions, each protrusion engaging a corresponding leaf spring on each side of the axle pin. The trip mechanism according to claim 1. 3. The fixed end of the leaf spring is fixed to the housing, the movable end supports a movable contact, and the movable end has a bifurcated shape defining two contact fingers, on each finger. The trip mechanism of claim 2 wherein there is one movable contact. 4. The leaf spring has a fixed end fixed to the housing, a movable end supporting a movable contact, the movable end having a bifurcated shape defining two contact fingers, on each finger. The trip mechanism of claim 1 wherein there is one movable contact. 5. A housing, a bistable armature mounted to the housing for pivotal movement between two stable positions, fixed contacts in the housing, one end fixed to the housing and the other end free. A pair of leaf springs at the ends and one of two stable positions to move to a closed position where it contacts the fixed contact, and the other of the two stable positions to move to an open position relative to the fixed contact. A movable contact, possibly supported by the free end, and a protrusion mounted on the armature for movement with the corresponding leaf spring, movable with the armature, and a latch supported by the armature and having a latching surface. An arm and a torsion spring attached to the housing and having latch fingers that engage the latch surface to hold the armature in one of two positions; A pusher reciprocally mounted in the housing to engage and disengage the latch finger and push down to engage the latch finger to disengage the latch finger from the latch surface and release the latch arm. Overload relay trip mechanism consisting of a button. 6. A housing, an armature movably mounted to the housing between the two positions, fixed contacts in the housing, and spacedly mounted in the housing, each fixed to the housing. A fixed end, a pair of leaf springs having a movable free end, a movable contact supported by the free end so as to be movable toward and away from the fixed contact, and an armature Means provided on the armature for engaging the leaf spring at a position spaced from the fixed end when moving between positions, and in cooperation with the armature, shifting the armature from at least one of the two positions to the other. A movable lever operable to operate, an operating means for the movable lever including an element movable towards and away from the lever, and a movable lever. A spring finger supported by one of the movable lever and the operating means and extending to the other of the movable lever and the operating means at an acute angle, and the spring finger when the operating means moves toward the movable lever when the armature is in the one position. And a stop surface on the other of the operating means and a movable lever arranged to disengage from and release the spring finger when the armature moves to the other of the two positions. A trip mechanism for the load relay. 7. The trip mechanism of claim 6 wherein the spring is a torsion spring with a coil mounted on the post and the spring finger extends from the coil. 8. The trip mechanism of claim 7 wherein the post is on the moveable lever and the stop surface is on the operating means. 9. The trip mechanism according to claim 8, wherein the operating means is a manual operating means. 10. The free end has a bifurcated shape that defines two contact mounting fingers, the movable contacts respectively located on the contact mounting fingers, and the fixed contacts each a bifurcated free end of a leaf spring. 7. The tripping mechanism of claim 6 which is a pair of fixed points arranged to be engaged by movable contacts on the section.